A Garch-based adaptive playout delay algorithm for VoIP

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.comnet.2010.06.006 Byline: Ying Zhang (a), Damien Fay (b), Liam Kilmartin (a), Andrew W. Moore (b) Keywords: ARMA; Garch; Playout delay; Time series forecasting; VoIP Abstract: Network delay, packet loss and network delay variability (jitter) are important factors that impact on perceived voice quality in VoIP networks. An adaptive playout buffer is used in a VoIP terminal to overcome jitter. Such a buffer-control must operate a trade-off between the buffer-induced delay and any additional packet loss rate. In this paper, a Garch-based adaptive playout algorithm is proposed which is capable of operating in both inter-talkspurt and intra-talkspurt modes. The proposed new model is based on a Garch model approach; an ARMA model is used to model changes in the mean and the variance. In addition, a parameter estimation procedure is proposed, termed Direct Garch whose cost function is designed to implement a desired packet loss rate whilst minimising the probability of consecutive packet losses occurring. Simulations were carried out to evaluate the performance of the proposed algorithm using recorded VoIP traces. The main result is as follows; given a target Packet Loss Rate (PLR) the Direct Garch algorithm produces parameter estimates which result in a PLR closer than other algorithms. In addition, the proposed Direct Garch algorithm offers the best trade-off between additional buffering delay and Packet Loss Rate (PLR) compared with other traditional algorithms. Author Affiliation: (a) Electrical & Electronic Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland (b) Computer Laboratory, University of Cambridge, UK Article History: Received 10 August 2009; Revised 9 April 2010; Accepted 3 June 2010 Article Note: (miscellaneous) Responsible Editor: N. Agoulmine